In the field of foundation engineering construction and resource/energy exploitation, such as transportation, water conservancy and hydropower and mining, it is required to construct a large number of deep-buried long and large tunnels (tunnels, laneways). TBM (full-section rock tunnel boring machine), by virtue of its unique advantages of safety, high efficiency, economy etc., becomes the optimal choice and the inevitable development orientation for construction of deep-buried long and large tunnels (tunnels, laneways). The excavation course of a TBM will cause continuous adjustment of the stress of the surrounding rock, prominently characterized by dramatic change in the main stress value together with wide-angle rotation of a principal stress axis. Under a condition of a deep-buried high stress, the aforesaid changes in the stress of the surrounding rock often result in the frequent occurrence of major engineering disasters such as high-strength rock burst, large deformation, machine jamming and the like, which are serious threats to the personnel and construction safety and cause huge economic losses. Therefore, in-depth reveal of surrounding rock breaking mechanism and mechanical characteristics under the combined condition of the change in the main stress value and the rotation of the principal stress axis of the surrounding rock when a TBM is tunneling in a deep stratum is the basic premise and scientific basis for the accurate prediction and reliable prevention and control of the aforesaid major engineering disasters, and is also a key factor to which major consideration should be given in the model selection of deep stratum TBMs and system adaptability design.
Among the existing domestic and foreign rock mechanics testing apparatuses, those capable of simulating a complex stress path include rock hollow cylinder torsional shear apparatuses. However, when they are working, the process of axial force application and the process of torque application will interfere with each other, resulting in reduction of the precision and reliability of the force exerted on a hollow rock sample; in addition, when a testing machine is in standby, there are safety problems such as rocking or collision of the force application assemblies suspended in the air.